S01 - Session O1 - Study of Rose RoFT transgenic plants

Authors: Laurence Hibrand-Saint Oyant *, Latifa Hamama, Julien Bosselut, Jérôme Chameau, Séverine Foucrier, Julien Jeauffre, Laurent Ogé, Tatiana THOUROUDE, Linda VOISINE, Fabrice FOUCHER

In the ornamental sector, the rose represents a study model due to its great variability, particularly in terms of seasonality of flowering. Non-recurrent roses bloom only in spring, whereas continuous flowering roses bloom during the whole growing season, attributed to these having lost flowering repressor RoKSN , a gene homologous to TFL1 . The floral transition involves competition between RoKSN and the activator of flowering FLOWERING LOCUS T (FT), both members of the phosphatidylethanolamine-binding proteins (PEBPs) family. To better understand the transition between vegetative to floral mechanisms, three rose cultivars were genetically transformed to overexpress RoFT and were genetically and phenotypically characterised. These three transformed cultivars showed different phenotypes in terms of floral organs, architecture and flowering date. Thus, one genotype has more petals, another fewer, while no difference was observed on the third one. A study of the genes regulated by RoFT ( RoSOC1, RoLFY, RoAP1 ) as well as the genes implied in the floral organ identity ( RoAP2, RoAG, RoFUL, RoAP 3) was carried out. In addition, as RoFT is a mobile protein, grafting studies were carried out by grafting a non-recurrent rose onto roses overexpressing RoFT . This study allowed us to understand the regulation of flowering in perennial species such as the rose, and to test the effect of different genetic backgrounds.